mercurial/filemerge.py

mdiff: compare content of binary files directly

A plain Python string comparison stops when the first mismatch is
found, whereas the call to md5 would need to compute the hash over the
entire string and only then do the comparison.

# filemerge.py - file-level merge handling for Mercurial
#
# Copyright 2006, 2007, 2008 Matt Mackall <[e-mail]>
#
# This software may be used and distributed according to the terms
# of the GNU General Public License, incorporated herein by reference.

from node import nullrev, short
from i18n import _
import util, os, tempfile, simplemerge, re, filecmp

def _toolstr(ui, tool, part, default=""):
    return ui.config("merge-tools", tool + "." + part, default)

def _toolbool(ui, tool, part, default=False):
    return ui.configbool("merge-tools", tool + "." + part, default)

def _findtool(ui, tool):
    if tool in ("internal:fail", "internal:local", "internal:other"):
        return tool
    k = _toolstr(ui, tool, "regkey")
    if k:
        p = util.lookup_reg(k, _toolstr(ui, tool, "regname"))
        if p:
            p = util.find_exe(p + _toolstr(ui, tool, "regappend"))
            if p:
                return p
    return util.find_exe(_toolstr(ui, tool, "executable", tool))

def _picktool(repo, ui, path, binary, symlink):
    def check(tool, pat, symlink, binary):
        tmsg = tool
        if pat:
            tmsg += " specified for " + pat
        if pat and not _findtool(ui, tool): # skip search if not matching
            ui.warn(_("couldn't find merge tool %s\n") % tmsg)
        elif symlink and not _toolbool(ui, tool, "symlink"):
            ui.warn(_("tool %s can't handle symlinks\n") % tmsg)
        elif binary and not _toolbool(ui, tool, "binary"):
            ui.warn(_("tool %s can't handle binary\n") % tmsg)
        elif not util.gui() and _toolbool(ui, tool, "gui"):
            ui.warn(_("tool %s requires a GUI\n") % tmsg)
        else:
            return True
        return False

    # HGMERGE takes precedence
    hgmerge = os.environ.get("HGMERGE")
    if hgmerge:
        return (hgmerge, hgmerge)

    # then patterns
    for pat, tool in ui.configitems("merge-patterns"):
        mf = util.matcher(repo.root, "", [pat], [], [])[1]
        if mf(path) and check(tool, pat, symlink, False):
                toolpath = _findtool(ui, tool)
                return (tool, '"' + toolpath + '"')

    # then merge tools
    tools = {}
    for k,v in ui.configitems("merge-tools"):
        t = k.split('.')[0]
        if t not in tools:
            tools[t] = int(_toolstr(ui, t, "priority", "0"))
    names = tools.keys()
    tools = util.sort([(-p,t) for t,p in tools.items()])
    uimerge = ui.config("ui", "merge")
    if uimerge:
        if uimerge not in names:
            return (uimerge, uimerge)
        tools.insert(0, (None, uimerge)) # highest priority
    tools.append((None, "hgmerge")) # the old default, if found
    for p,t in tools:
        toolpath = _findtool(ui, t)
        if toolpath and check(t, None, symlink, binary):
            return (t, '"' + toolpath + '"')
    # internal merge as last resort
    return (not (symlink or binary) and "internal:merge" or None, None)

def _eoltype(data):
    "Guess the EOL type of a file"
    if '\0' in data: # binary
        return None
    if '\r\n' in data: # Windows
        return '\r\n'
    if '\r' in data: # Old Mac
        return '\r'
    if '\n' in data: # UNIX
        return '\n'
    return None # unknown

def _matcheol(file, origfile):
    "Convert EOL markers in a file to match origfile"
    tostyle = _eoltype(open(origfile, "rb").read())
    if tostyle:
        data = open(file, "rb").read()
        style = _eoltype(data)
        if style:
            newdata = data.replace(style, tostyle)
            if newdata != data:
                open(file, "wb").write(newdata)

def filemerge(repo, mynode, orig, fcd, fco, fca):
    """perform a 3-way merge in the working directory

    mynode = parent node before merge
    orig = original local filename before merge
    fco = other file context
    fca = ancestor file context
    fcd = local file context for current/destination file
    """

    def temp(prefix, ctx):
        pre = "%s~%s." % (os.path.basename(ctx.path()), prefix)
        (fd, name) = tempfile.mkstemp(prefix=pre)
        data = repo.wwritedata(ctx.path(), ctx.data())
        f = os.fdopen(fd, "wb")
        f.write(data)
        f.close()
        return name

    def isbin(ctx):
        try:
            return util.binary(ctx.data())
        except IOError:
            return False

    if not fco.cmp(fcd.data()): # files identical?
        return None

    ui = repo.ui
    fd = fcd.path()
    binary = isbin(fcd) or isbin(fco) or isbin(fca)
    symlink = 'l' in fcd.flags() + fco.flags()
    tool, toolpath = _picktool(repo, ui, fd, binary, symlink)
    ui.debug(_("picked tool '%s' for %s (binary %s symlink %s)\n") %
               (tool, fd, binary, symlink))

    if not tool:
        tool = "internal:local"
        if ui.prompt(_(" no tool found to merge %s\n"
                       "keep (l)ocal or take (o)ther?") % fd,
                     _("[lo]"), _("l")) != _("l"):
            tool = "internal:other"
    if tool == "internal:local":
        return 0
    if tool == "internal:other":
        repo.wwrite(fd, fco.data(), fco.flags())
        return 0
    if tool == "internal:fail":
        return 1

    # do the actual merge
    a = repo.wjoin(fd)
    b = temp("base", fca)
    c = temp("other", fco)
    out = ""
    back = a + ".orig"
    util.copyfile(a, back)

    if orig != fco.path():
        repo.ui.status(_("merging %s and %s to %s\n") % (orig, fco.path(), fd))
    else:
        repo.ui.status(_("merging %s\n") % fd)

    repo.ui.debug(_("my %s other %s ancestor %s\n") % (fcd, fco, fca))

    # do we attempt to simplemerge first?
    if _toolbool(ui, tool, "premerge", not (binary or symlink)):
        r = simplemerge.simplemerge(a, b, c, quiet=True)
        if not r:
            ui.debug(_(" premerge successful\n"))
            os.unlink(back)
            os.unlink(b)
            os.unlink(c)
            return 0
        util.copyfile(back, a) # restore from backup and try again

    env = dict(HG_FILE=fd,
               HG_MY_NODE=short(mynode),
               HG_OTHER_NODE=str(fco.changectx()),
               HG_MY_ISLINK='l' in fcd.flags(),
               HG_OTHER_ISLINK='l' in fco.flags(),
               HG_BASE_ISLINK='l' in fca.flags())

    if tool == "internal:merge":
        r = simplemerge.simplemerge(a, b, c, label=['local', 'other'])
    else:
        args = _toolstr(ui, tool, "args", '$local $base $other')
        if "$output" in args:
            out, a = a, back # read input from backup, write to original
        replace = dict(local=a, base=b, other=c, output=out)
        args = re.sub("\$(local|base|other|output)",
                      lambda x: '"%s"' % replace[x.group()[1:]], args)
        r = util.system(toolpath + ' ' + args, cwd=repo.root, environ=env)

    if not r and _toolbool(ui, tool, "checkconflicts"):
        if re.match("^(<<<<<<< .*|=======|>>>>>>> .*)$", fcd.data()):
            r = 1

    if not r and _toolbool(ui, tool, "checkchanged"):
        if filecmp.cmp(repo.wjoin(fd), back):
            if ui.prompt(_(" output file %s appears unchanged\n"
                "was merge successful (yn)?") % fd,
                _("[yn]"), _("n")) != _("y"):
                r = 1

    if _toolbool(ui, tool, "fixeol"):
        _matcheol(repo.wjoin(fd), back)

    if r:
        repo.ui.warn(_("merging %s failed!\n") % fd)
    else:
        os.unlink(back)

    os.unlink(b)
    os.unlink(c)
    return r